Content addressed storage (CAS) devices store typically fixed content, perhaps from many sources, in a storage server typically accessed via a network. An example is the Centera™ CAS device made and sold by EMC™ Corporation of Hopkinton, Mass. Typically, an application sends data to the CAS device to be stored, the CAS device determines a storage location by calculating a “content address” (CA) based at least in part on the content to be stored, after which the CAS device stores the content in the selected location and returns the content address to the application that sent the data. The content address is used like a claim check to enable the storing application (or, in theory, another application to which the CA has been provided) to retrieve (and in some cases perform other limited operations, e.g., delete) the previously stored content.
In a typical CAS device, the same management policies, e.g., data retention policies, are applied to all data, regardless of the source. A typical CAS device has no native file system or other way to identify a particular data object as coming from a particular source (e.g., application). In many cases, however, different policies may apply to different data, depending e.g., on the content and/or the application or other process that created and/or stored the data. In current CAS devices, normally the more restrictive (e.g., longest retention period) policy is applied to all data, which results in some data being retained, e.g., much longer than is required, needlessly tying up storage resources that could otherwise be used to store other data. Therefore, there is a need for a way to apply application (or other data set) specific management policies, such as data retention policies, to data stored in a CAS device.